my dad left my motor out with no tarp on it and now it has surface rust on the piston walls is there any way to save my motor

 

If it's a very very slight amount you can clean it off with a "bottle brush hone" chucked in a drill. I've also used an old, rough, terry cloth towel sprayed down with penetrating oil and LOTS of elbow grease. If it's heavier than that you need to get a shop to hone it out again.

 

it can be done??

 

Oh, yes. If it's not too bad then it can definitely be done. I've done it myself several times on engines that had gotten a little surface rust in the bores from sitting a while (usually in my damp basement) before assembly.